//
//  ProblemOffer09.swift
//  TestProject
//
//  Created by 武侠 on 2021/7/5.
//  Copyright © 2021 zhulong. All rights reserved.
//

import UIKit

/*
 剑指 Offer 09. 用两个栈实现队列 ✅
 用两个栈实现一个队列。队列的声明如下，请实现它的两个函数 appendTail 和 deleteHead ，分别完成在队列尾部插入整数和在队列头部删除整数的功能。(若队列中没有元素，deleteHead 操作返回 -1 )

 示例 1：
     输入：
     ["CQueue","appendTail","deleteHead","deleteHead"]
     [[],[3],[],[]]
     输出：[null,null,3,-1]
 示例 2：
     输入：
     ["CQueue","deleteHead","appendTail","appendTail","deleteHead","deleteHead"]
     [[],[],[5],[2],[],[]]
     输出：[null,-1,null,null,5,2]
 提示：
     1 <= values <= 10000
     最多会对 appendTail、deleteHead 进行 10000 次调用
 */

class CQueue {
    var inputList:  [Int] = []   // 插入栈
    var deleteList: [Int] = []   // 删除栈
    init() {
    }
    
    func appendTail(_ value: Int) {
        inputList.append(value)
    }
    
    func deleteHead() -> Int {
        if deleteList.isEmpty == true {
            while inputList.isEmpty == false {
                deleteList.append(inputList.removeLast())
            }
        }
        if deleteList.isEmpty == false {
            return deleteList.removeFirst()
        }
        return -1
    }
}
@objcMembers class ProblemOffer09: NSObject {
    func solution() {
        let obj = CQueue()
        obj.appendTail(4)
        let ret_2: Int = obj.deleteHead()
        print("delete ", ret_2)
    }
}
